Separation of tar acids and tar bases



United States Patent SEPAR" ATION'OF' TAR ACIDS TAR. EASES EverettGorin,- Pittsburgh, Benjamin W. Jones? Bridgeville and- Martin INan-worth; Pittsburgh, Pal, assignors" to PittsburghQonsolidsificmfioal: Company; Pittsburgh, Pa.,-. a corporation ofPennsylvania No Drawing. A'pplicatious eptember'2 8; 1'953, Serial No.382;866*

7 Claims. (CL260-627);

'lhisinvention relates to the ion=exehange treatment of mixtures oftaracid'si; e. phenols,.an'd tar bases i. e. organicnitrogen containing.bases, to street separation and-permitrecovery'of the tar acid'sinsubstantially'tar base free condition;

This application'is a continuationdn-part of our" co pendingapplication; Serial Number 215376, filedMatch 13; 1951, now abandoned,and assigned to? the a's'signee of-the present invention;

Tar acidsand tarbases -are' foundtogetherinthe liquid products ofdistillation of" oil shale and low temperature carbonization" of coaland also in" the s'o-called petroleum cres'ylics produced by' thecracking of petroleum. The tar acids are' particularly. valuablecommercially in. the production of'resins, plastici'zers'and the like:In such uses their utility'is" seriously impaired if they arecontaminatedby tar bases? Unfortunately, thebo'ilingpoints of thetaracidsand'thetar bases derivedfromth'e abovementioned' source's are suchas'not to'permit their'efie'c'tive separation by distillation: Treatmentof the mixtures with strong'acid s is'only partially successful inremoving the tar-bases and isparticularly-ineffective for removingthosebases which boil' above 230" C In accordancewiththis-invention, wehave'found that treatment of a mixture of taracids and tar baseswith acation exchangeresinisextremely efiective'in'rernovin'g not only the low'boiling' tar bases butalso' the high boiling tar bases, therebyleavingthe tar acids in a'substantially ta'rbase free condition.

Furthermore, we' have discovered'- that the capacity of the r'esintoadsorb. the'tar' bases is commercially satis-' factory and also thatthe" resin can be-r'eadily-a'nd completely regenerated by acid dissolvedin apolar solvent in which the" tarba'ses aresolhble.

In the aforementioned application, the treatment of the; mixture-of taracids and tarbases w'ith' a cation ex"- c-hange resinw'asdescrib'eda'sb'eing carried outin a polar solvent; We have sincefo'und that-the useof a polar solvent is'desirable'in'some cases but not necessary; Nosolvent at all ora': non-polarsolvent may-'beemployed. However, thepreferred embodiment of theproeessstill includes the use of a polarsolvent. One reason for this is the fact that the tar acids and basesare recovered in a solution of a polar solvent e. g.- methanol in theseparation oftar acids from neutraLoiLby thecountercurrent eittractivetreatment of'tar acid oil with. aqueous methanol'andhex'aneasdescribed'in the copending application of Gorin and Neuworth, SerialNumber 184,474, now US. Patent 2,666,796,-file'd- March 13, 1951, andassigned to the assignee of the presentinvention. There is, therefore,no need to' remove the polar solvent before proceeding with: the ionexchange treatment. Furthermore, it is som'etimes desirable to have 1 asolvent toreduce the viscosity of the feedstock, particularlywhen'hig'hboiling tar acids are present.

Specifically, the preferred method of treatment is as follows. Themixture of tar acids and tar bases is first dissolved in a polarsolvent. Examples of such solvents 2. are methanol, ethanol, propane],acetone, and methyl ethyl ketone. Preferably the solvent is in anaqueous condition, the amount of water being insufficient to render thetar acids and the tar bases insoluble in the polar solventr Thepreciseamount ofwaterthat may be tolerated varies,- of course, with thecomposition of the tar acids, as well as their concentration, but may:easily be determined by simple solubility tests on the mixture. We havefound aqueous methanol to be particularly effective. Since the lattersolvent is' also useful in separating tar acids and tar-bases from theneutral' oil with which" they generally occur in: the distillatefractions derived from distillation of coal, oil shale and thelike',-theresulting extract may be used directly: in the presentinvention.

The solution of tar acids and bases is passed" through abed-of. granularcation exchange resin; Useful ag'e'nts of this type are thecationicexchange: resins containing. acidic groups, for example, the sulfonatedphenolic typev cation exchanger, the sulfonated coal type cation exchangen'the sulfonated styrene-type cation'exchanger, as wellas: thecorrespondingcarboxylic cation exchangers. We: prefer to use those 1cation' exchange resins which derive their capacity. toadsorb-essentially from sulfonic acid groups. As a result ofcontacting.the solution of tar acids and bases with the resin, the bases areadsorbed upon the resin andasolutionoi tar acids substantially freeoftar bases is discharged from the bed of resin. The solvent maythenbe-removed by distillationandthe tar acids. recovered.

After the cation exchangeresinhas adsorbed asnfiicient quantity of thetar bases, so thatit-approachesthe point at which it will not'adsorbany. more, or the point at which an appreciable amount of tar basesappears in the efiluent, the resin is eluted, preferably by a strongacid such as hydrochloric or sulfuric in a' polar solvent in which thetar bases are likewise soluble. While the solvent may advantageouslycontain some water, the amount of water must not be suflicienttopreventthe bases from being completely dissolved; or the capacity of the resinto adsorb in subsequent cycles of treatment will be seriously impaired.The polar solvent may be the same polar solvent selected for the baseadsorption treatmentand isa'gain preferably aqueous methanol. As aresult of the=elution ofthe resin, an extract containing thetar'bases inthe fiorm of their mineral acid salts together with free acid is'obtained' The tar bases may readily be'recove'red from this extract bydecomposing the salts with strong'alkali followed by distillation; Incontrast to the optional use of a polar solvent in the treatment of thefeedstock with the resin, the use of a polar solvent in the regenerationof the resin. is critically essential; Attempts-to remove the adsorbedbases with outthe polarsolvent were unsuccessful.

The relative concentrations of tar acids: and ta'r'bases in the originalsolution do not appean to be critical in thesuccessful practice of ourinvention. In general; however, the-tarbases-are present in=a very.small a'mount as: compared with-thetar acids, i. e. upto ab'o'ut 2l'0%'of thertotal t'ar acids.

In-the followingztable are 'tabulatedthe data obtained by-treatinganiix-ture of tar acids and tar bases derived frcm thedi's'tillationofbituminous' coalat about 850 F? with sutfonated cationexchangers; Runs 1' and" 2 em: played a altwater phenolic type resinsold under the trademark Amberlite IR- by Resinous Productsan'dChemicalCompany; Rim fem'plbYed a sulfonatedcoal resin sold under thetrademark ZemKarb by the Permutit Company. In all three runs, themixture of tar acids and tar bases were dissolved in 70% aqueousmethanol (i. e. 70 parts by volume of CI-IsOH and 30 parts by volume ofwater). Likewise, in all three runs the resin was regenerated by asolution of 4% H01 in 70% aqueous methanol.

Resin capacity calculations have'been made on eflluents at break throughpoint.

The following example illustrates the application of our process toamixture of tar acids and bases without the use of a solvent. A mixtureconsisting of 99.78% by weight of tar acids and 0.22% by weight of tarbases was passed over a sulfonated phenolic type resin sold under thetrademark Amberlite IR-l20 by Resinous Products and Chemical Company.The effiuent tar acids contained 0.07% by weight of tar bases. Theregeneration of the resin is accomplished in the same manner asdescribed above.

According to the provisions of the patent statutes, we have explainedthe principle, preferred construction, and mode of operation of ourinvention and have illustrated and described what we now consider torepresent its best embodiment. However, we desire to have it understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than as specifically illustrated and described.

We claim:

1. The method of removing contaminating quantities of tar bases from amixture consisting essentially of tar acids and tar bases derived fromlow temperature carbonization tar which comprises continuously passingsaid mixture in intimate contact with a cation exchange resin wherebysaid tar bases are adsorbed on said resin and said tar acids are passedthercthrough, continuously collecting the effiuent liquid which haspassed through said cation exchange resin, said eflluent liquidcontaining tar acids substantially free of tar bases, until said resinbecomes substantially saturated with tar bases, thereafter regeneratingsaid resin by passing therethrough a solution of strong acid in anaqueous polar solvent selected from the class consisting of methanol,ethanol, propanol, acetone and methyl ethyl ketone to desorb said tarbases from said cation exchange resin, recovering said solution ofstrong acid in an aqueous polar solvent containing desorbed tar bases,and repeating the entire process in cyclic fashion.

2. The method of removing contaminating quantities of tar bases from amixture consisting essentially of tar acids and tar bases derived fromlow temperature carbonization tar which comprises preparing a solutionof said mixture in a polar solvent selected from the class consisting ofmethanol, ethanol, propanol, acetone and methyl ethyl ketone,continuously passing said solution in intimate contact with a cationexchange resin whereby said tar bases are adsorbed on said resin andwhereby said tar acids and polar solvent are passed therethrough, andcontinuously collecting the efiluent liquid which has passed throughsaid cation exchange resin, said efiiuent liquid containing tar acidssubstantially free of tar bases dissolved in said polar solvent, untilsaid resin becomes substantially saturated with tar bases, thereafterregenerating said resin by passing therethrough a solution of strongacid in an aqueous polar solvent selected from the class consisting ofmethanol, ethanol, propanol, acetone and methyl ethyl ketone to desorbsaid tar bases I from said cation exchange resin, recovering saidsolution of strong acid in an aqueous polar solvent containing desorbedtar bases, and repeating the entire process in cyclic fashion.

3. The method according to claim 2 in which the tar bases comprise tarbases boiling above 200 C;

4. The method according to claim 2 in which the cation exchange resin isone which derives its exchange capacity essentially from acid groups.

5. The method according to claim 2 in which the cation exchange resin isone which derives its exchange capacity essentially from sulfonicgroups.

6. The method of removing contaminating quantities of tar bases from amixture consisting essentially'oftar acids and tar bases derived fromlow temperature carbonization tar which comprises preparing a solutionof said mixture in a polar solvent selected from the class consisting ofmethanol, ethanol, propanol, acetone and methyl ethyl ketone,continuously passing said solution in intimate contact with a cationexchange resin whereby said tar bases are adsorbed on said resin andwhereby said tar acids and said polar solvent are passed therethrough,continuously collecting the efiluent liquid which has passed throughsaid cation exchange resin, said efliuent liquid containing tar acidssubstantially free of tar bases, dissolved in said polar solvent untilsaid resin becomes substantially saturated with tar bases, thereafterregenerating said resin by passing therethrough a solution of strongacid in aqueous methanol to desorb said tar bases from said cationexchange resin, recovering said solution of strong acid in aqueousmethanol containingdesorbed tar bases, and repeating the entire processin cyclic fashion. 7. The method of removing contaminating quantities oftar bases from a mixture consisting essentially of tar acids and tarbases derived from low temperature carbonization tar which comprisespreparing a solution of; said mixture in a polar solvent selected fromthe class consisting of methanol, ethanol, propanol, acetone and methylethyl ketone, continuously passing said solution in intimate contactwith a cation exchange resin whereby said tar bases are adsorbed on saidresin and whereby said tar acids and said polar solvent are passedtherethrough, continuously collecting the eflluent liquid which haspassed through said cation exchange resin, said efiluent liquidcontaining tar acids substantially free of tar bases dissolved in saidpolar solvent, until said resinbecomes substantially saturated with tarbases, thereafter regenerating said resin by passing therethrough asolution of strong acid selected from the class consisting of sulfuricacid and hydrochloric acid, in aqueous methanol to desorb said tar basesfrom said cation exchange resin, recovering said solution of strong acidin aqueous methanol containing desorbed tar bases, and repeating theentire process in cyclic fashion.

References Cited in the file of this patent 260-B. E. Digest.

2. THE METHOD OF REMOVING CONTAMINATING QUANTITIES OF TAR BASES FROM AMIXTURE CONSISTING ESSENTIALLY OF TAR ACIDS AND TAR BASES DERIVED FROMLOW TEMPERATURE CARBONIZATION TAR WHICH COMPRISES PREPARING A SOLUTIONOF SAID MIXTURE IN A POLAR SOLVENT SELECTED FROM THE CLASS CONSISTING OFMETHANOL, ETHANOL, PROPANOL, ACETONE AND METHYL ETHYL KETONE,CONTINUOUSLY PASSING SAID SOLUTION IN INTIMATE CONTACT WITH A CATIONEXCHANGE RESIN WHEREBY SAID TAR BASES ARE ADSORBED ON SAID RESIN ANDWHEREBY SAID TAR ACIDS AND POLAR SOLVENT ARE PASSED THERETHROUGH, ANDCONTINUOUSLY COLLECTING THE EFFLUENT LIQUID WHICH HAS PASSED THROUGHSAID CATION EXCHANGERESIN, SAID EFFLUENT LIQUID CONTAINING TAR ACIDSSUBSTANTIALLY FREE OF TAR BASES DISSOLVED IN SAID POLAR SOLVENT, UNTILSAID RESIN BECOMES SUBSTANTIALLY SATURATED WITH TAR BASES, THEREAFTERREGENERATING SAID RESIN BY PASSING THERETHROUGH A SOLUTION OF STRONGACID IN AN AQUEOUS POLAR SOLVENT SELECTED FROM THE CLASS CONSISTING OFMETHANOL, ETHANOL, PROPANOL, ACETONE AND METHYL ETHYL KETON TO DESORBSAID TAR BASES FROM THE CATION EXCHANGE RESIN, RECOVERING SAID SOLUTIONOF STRONG ACID IN AN AQUEOUS POLAR SOLVENT CONTAINING DESORBED TARBASES, AND REPRATING THE ENTIRE PROCESS IN CYCLIC FASHION.